Shi'er Shengxiao (the Twelve Animals of Chinese Zodiac)

Shi' er shengxiao or shi' er shuxiang is a kind of Chinese folk custom. It is a way to designate the years in the names of the animals. The twelve animals actually represent the twelve earthly branches, one animal symbolizing one year. On many occasions, when someone is asked about his age, he will reply by naming the animal of the year in which he was born, e. g. the year of the ox, or the year of the dragon, etc. Thus it is evident that the twelve animals are deeply rooted among the people. Chinese Folklores & Festivals Website

It is generally agreed that the association of the twelve earthly branches and the twelve animals started in the Eastern Han Dynasty (25---220 A. D.) and gained popularity in the first century A.D. Since the lunar calendar was formally adopted in the Han Dynasty, according to which the years were designated by the heavenly stems and the earthly branches, it is therefore logical to combine the twelve earthly branches with the twelve animals to designate the years. This can be verified in the book Shuo Wen Jie Zi. Its explanation of the character si, one of the twelve branches, goes like this: "It is a pictographic character indicating the shape of a snake." We can also find records in another book, The Annals of Wu and Yue, written in the first century. There was a passage about the relevance between chen (another earthly branch) and the drag on and between si and the snake, which further proved that the combination of the branches and the animals was already widely adopted in the first century. 1155815

Chinese Folklores & Festivals Website